Roller path inclination compensator

ABSTRACT

A roller path inclination compensator for providing electrical signals for compensating errors in aiming a gun due to an inclined gun mount. An inclined gun mount is measured to determine the roller path inclination angle and the location, in train, of the high point of the roller path. The inclination angle and the location of the high point are set into the compensator, and the compensator modifies course synchro orders to provide a train correction and an elevation correction which are applied in series with the train and elevation CT rotors in a gun mount.

nited States Paten [19] Cox et al. June 5, 1973 54] ROLLER PATH INCLINATION 3,465,135 9/1969 Belsterling etal ..235/1s9 COMPENSATOR 2,223,?2; geiiltnce a 10 [75] Inventors: James R. Cox; Carlon N. Turner,

both of Louisville, Ky. OTHER PUBLICATIONS [73] Assignee; The United States of A i as Textbook: Korn & Korn: Electronic Analog Compurepresented by the Secretary of the ters McGraw-Hrll 1956, pages 399-407. Navy, Washington, DC. Primary Examiner-Felix D. Gruber [22] Fled: 1972 Attorney-R. S. Sciascia, H. H. Losche, Paul S. 21 Appl. No.: 234,016 Colhgnon [57] ABSTRACT [52] Cl "235/615 89/41 2 A roller path inclination compensator for providing 51 I Cl G06 7 80 electrical signals for compensating errors in aiming a nt. 6gl 5IE gun due to an incIined gun mount An inched gun [58] held of Search l mount is measured to determine the roller path 235/615 inclination angle and the location, in train, of the high 197; 89/41 41 41 41 41 ME point of the roller path. The inclination angle and the location of the high point are set into the compensa- [561 References Cited tor, and the compensator modifies course synchro orders to provide a tram correction and an elevation UNITED STATES PATENTS correction which are applied in series with the train 3 5 I27 67 D I 235/186 X and elevation CT rotors in a gun mount.

0 an 3,464,016 8/1969 Kerwin et a1. ..235/ 186 X 3 Claims, 5 Drawing Figures OUTPUT INPUT INTERFACE SECTION I ANALOG COMPUTATION SECTION INTERFACE I I SECTION SINIEI I I Z I {39 I SCAL'E I5'\. ing ADJUST I I ELEvATIoN Is ot EToR F'LTER FISWEEPIEFIIR- I DEMOD GENERATOR AND I SIN E FILT R I cos E cosIEI m I I SIN(E) sINIT-EI I SHIP'S cos E ELEVATION F REFERENCE 40 SYNCHRO RE SQUARING I f i REFERENcE AMP AM PLIFIER I I MULTI- P I I3 I LER l POTENTl- FUNCTION IMULTI I 74 I- oM TER GENERATOR PLIER F I SIN (T-B) l SHIP'S TRAIN REF REFERENcE I 56 67 L38 I SYNCHRO SQUARING REFERENCE AMP AMPLIFIER I I I I sIN(T-BI I I I LINEOR DE A D I E II D|FFERENT|AL mg FILTER I I ORDERS TRANSMITTER @ggggggg I I I 1 IB NET "'3 P FILTER FL LvAI'IoN COS T-Bl +2! .37 QB I mRRILIION PAIENIIZL 5I975 3.737. 630

sum 1 OF 4 COMPENSATOR ELEV ELEV IX CORRECTION ORDER TRAIN IX ORDER TRAIN CORRECTION TRAIN CTS DIRECTOR TRAIN IX ORDER TRAIN 36X ORDER ELEV CTS ELEV IX ORDER ELEV 36X ORDER F 2 GUN MOUNT BACKGROUND OF THE INVENTION The invention described herein relates to an electronic device for compensating error created by nonparallelism between the roller path of a fire control director and the roller path of an associated gun mount.

Present military specifications require that the roller paths of a reference fire control director and its associated gun mounts be parallel within plus or minus 3 minutes of are. This degree of parallelism is originally obtained by very accurate machining of the director and gun foundations prior to installation of ordnance items. Structural distortion of a vessel s deck is frequently caused by loading, rough seas, temperature change, and the like, and this distortion can cause roller path non-parallelism which exceeds design specifications. As a result of excessive non-parallelism between the roller paths of a director and its associated gun mount, errors in train and elevation will seriously degrade gun system accuracy.

One method of correcting excessive error caused by non-parallelism is to remachine the gun roller path to its design specification. This method, however, is very expensive and, additionally, the gun roller path can again change due to additional ship distortion. Accordingly, various compensators have been devised to compensate for roller path error of a gun turret.

One such compensator is shown and described in U. S. Pat. No. 2,762,266, entitled, Roller Path Compensator, which issued Sept. 11, 1956, to Alfred A. Wolf. in this patented device, a gun which is automatically directed in elevation has its position automatically compensated for roller path error by adding a correction signal proportional to the sine of the azimuth train angle. Selsyn transmitters and receivers and a servo amplifier are employed to provide the necessary commands from a gun director to a gun turret and an autotransformer is provided to add a correction voltage to the servo amplifier to compensate for roller path error.

Another fire control compensating device is shown in U. S. Pat. No. 3,566,743, entitled, Kinematic Device For Fire Control Against Terrestrial Targets With Single Rate Sensor, which issued Mar. 2, 1971, to Millard M. Frohock, Jr. This correction device was primarily designed for use on land vehicles, such as military tanks or artillery field pieces that travel over rough terrain, and are required to fire at moving targets. In this device, a single rate sensor is provided to sense the azimuthal rate of a gun platform and a gravity sensor is provided to detect the angle by which the gun platform is off of horizontal. This gravity sensor takes the form of a resolver which accepts rate information to provide elevational and azimuthal gun pointing correction on a target.

SUMMARY OF THE INVENTION The present invention relates to a compensating device for correcting error due to non-parallelism between the roller path of a gun director and the roller path of a gun. The high point of error of a roller path and its position are first determined, and then geometric equations are solved to determine train correction and elevation correction for any position along the roller path. The compensator has a special purpose analog computer which takes elevation and train orders and solves correction equations for train and elevation.

The compensator then provides output signals whose magnitudes are proportional to the angles of correction. These correction signals are applied in series with the train and elevation rotors in a gun mount.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view showing angular relationship of roller path errors;

FIG. 2 is a block diagram showing a roller path inclination compensator connected to a gun system;

FIG. 3 is a block diagram of a preferred embodiment of the present invention; and

FIGS. 4(a) and 4(b), taken together, are a schematic diagram of a preferred embodiment of the present in vention. r, W a

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1 of the drawings, a reference plane X-Y is shown and this represents the roller path plane of a gun director. A direction of pointing a gun barrel can be specified by a train angle T and an elevation angle E. Assuming no parallax error, if the roller path plane of a gun will follow the director and point along the same line as the director, as represented by vector G. If the gun roller path plane is tilted with respect to the director roller path plane, as represented by plane X'-Y', the gun will point along the line represented by vector G. Therefore, a train pointing error and elevation pointing error are created whose magnitude varies depending on the degree of non-parallelism,

" that is, the amount of roller path inclination, and the train angle of the inclination high point. The geometric equations for train and elevation correction are as follows:

Tc A Tan(E) Sin (T-B);

Es A Cos (T-B);

Tc 5 t; and

Ec E e.

where A roller path inclination angle;

E elevation angle order;

T train angle order;

B location (train angle) of gun roller path high point;

t train error; and

e elevation error.

As shown in FIG. 2 of the drawings, roller path inclination compensator 8 of the present invention is designed for use with an existing gun director 9 and gun mount 10. Gun director 9 provides high speed orders (36X) to the control transformers (CTs) on gun mount 10 and also low speed orders (1X). Compensator 8 takes the low speed course (1X) synchro orders as inputs and solves equations (1) and (2) above. Compensator 8 outputs AC signals whose magnitudes are proportional to the angles of correction, and correction signals are applied in series with the train and elevation CT rotors in gun mount 10. The use of control transformers on gun mounts is well-known in the ordnance art and a more complete discussion is provided in the text, Naval Ordnance and Gunnery, Vols 1 and 2 (1955), Prepared by Department of Ordnance and Gunnery, United'States Naval Academy, and published by Superintendent of Documents, U. S. Government Printing Office.

Referring now to FIG. 3 of the drawings, the block diagram has been divided into three sections for purpose of explaining the present invention. There is designated an input interface section, an analog computation section and an output interface section. The input interface section processes incoming gun position or- .ders and sends themto the analog computer section in the proper form and at the required voltage levels. The analog computation section performs the necessary function to solve equations ("1) and (2), listed above, and the output interface section develops the proper signal levels for use by the gun mount synchros.

INPUT INTERFACE SECTION The input interface section is comprised of reference isolation amplifiers 11 and 12, reference squaring amplifiers 13 and 14, elevation and train sine/cosine generators 15 and 16, sine and cosine demodulators and filters 17, 18, 19, and 21, and a synchro differential transmitter 22 for shifting the high point angle, B. Synchro differential transmitters are well-known in the ordnance art and are fully described in Military Standardization Handbook 225(AS), entitled, Synchros- Description And Operation, published by Department of the Navy (Oct 1968). As shown in FIGS. 3 and 4 of the drawings, reference isolation amplifier 11 receives an input from the ships elevation synchro and scales down the voltage to a usable value. By way of example, the ships reference voltage might be 1 15 VAC and this is scaled down to a usable 8 VAC. Resistors 23 and 24 are equal in resistance value and also resistors 25 and 26 are equal. The gain is the simple ratio of the value of resistor 25 to the value of resistor 24. Diodes 27 and 28 provide overvoltage protection for amplifier 1 l. The associated circuitry for amplifier 12 is similar to that for amplifier 111 and consists of resistors 31 through 34 and diodes 35 and 36.

The output of reference isolation amplifier 11 is supplied to reference squaring amplifier 13 and to multiplier 37 in the analog computation section and, likewise, the output of reference isolation amplifier 12 is supplied to reference squaring amplifier 14 and multiplier 38. Reference squaring amplifiers 13 and 14 each transform a sine wave input into a square wave at the fundamental frequency. The output of each amplifier 113 and 14 is a square wave symmetrical about zero volts and alternating between +15 volts and 15 volts. This square wave switching function is then in the necessary form to operate the field effect transistor switches 41 and 41', in phase sensitive demodulators l7 and 18. The operation of reference squaring amplifiers 13 andll4 are similar, therefore, only a description and operation for amplifier 14 will be given. Reference squaring amplifier 14 operates such that two high gain level shifts occur to obtain plus and minus 15 volt outputs. During the negative segment of the input sine wave, transistor 42 is turned on when the base voltage is approximately zero volts and stays on until the value peaks in a negative direction and returns to approximately zero volts. During this half cycle, the collector of transistor 42 is virtually at ground potential. This allows current to flow in the base circuit of transistor 43 and drives it into saturation, pulling the output to 15 volts. During the positive segment of the base voltage, transistor 42 is turned off with diode 44 protecting transistor 42 from excessive reverse baseemitter voltage. When transistor 42 is off, no current flows in the base of transistor 43, which is also off", and the output, which is connected to a very high impedance, goes to plus 15 volts.

The roller path compensator of the present invention utilizes a sine/cosine generator 15 for elevation gun orders and also another sine/cosine generator 16 for train gun orders. The operation of these two sine/cosine generators are similar, therefore, only the elevation sine/- cosine generator will be described. The purpose of the sine/cosine generator 15 is to convert the elevation synchro order input into a sine and cosine function. This conversion is performed by amplifiers 45 and 46 and associated resistors. Resistors 47, 48, and 49 are equal in resistance and, therefore:

Elevation cosine output (2) RSI/R47 (E Cos (3) and as the value of resistors 52 and 53 are made equal, therefore:

Elevation sine output 1.732) R54/R53 (E Sin (4) Likewise, the train sine/cosine generator 16 provides: Train cosine output (2) R61/R57 (T (Cos (5) and Train sine output (L732) R64/R63 (T Sin (T-B). (6)

The terms E and T are used to denote the maximum line-to-line voltage of the elevation and train synchro lines, respectively. Since amplifiers 45, 46, 55, and 56 operate with a maximum output voltage of plus or minus ten volts, the RMS output value is limited to 5 volts RMS.

Four demodulator-filters are employed in the compensator with one each being used for the sin (E), cos (E), sin (T-B) and cos (T-B) outputs of the sine/cosine generators. All four demodulator-filters 17, 18, 19, and 21 are identical and the following description relates to the cos (E) demodulator-filter 18. The purpose of the demodulator section 61 of demodulator-filter 18 is to convert the AC RMS voltage input to a DC output voltage. The phase sensitive detector has two inputs, that is, the signal to be demodulated and the square wave switching function which contains the phasing information. The detector has two gains, depending upon the binary state of transistor 41'. When transistor 41' is on, the amplifier has a gain of plus one and, conversely, when transistor 41' is off, the amplifier has a gain of minus 1. The active filter section 62 of demodulator-filter 18 is a two-pole Butterworth filter with a double-break point at 14 Hz. The damping coefficient is 0.7 giving minimum response time and maximum flatness of the gain curve. The 120 Hz ripple component of the full wave Hz rectified input is attenuated by 20 db. A gain factor of approximately three is developed by the ratio of the value of resistor 63 to the value of resistor 64, which is the full amplifier output capability of approximately plus or minus VDC from a 3V RMS input.

A standard Navy synchro differential transmitter 22 ANALOG COMPUTATION SECTION The function of the analog computation section is to provide the desired mathematical operations of multiplication and division to solve equations (1) and (2). The elevation signal is demodulated, with the output from demodulator and filter 21 being Cos (TB). AC is reinserted with the proper phase into multiplier 37 and the output of multiplier 37 goes to potentiometer 68 and then to the output section for amplification. Potentiometer 68 is used to input the roller path inclination angle A.

In order to solve equation (1) for train correction, the output of demodulator and filter 17 is divided by the output of demodulator and filter 18 in divider 39.

A scale adjust potentiometer 29 is provided between demodulator and filter l7 and divider 39 and is used to scale the elevation sine function output voltage prior to application to the analog computer section. Potentiometer 29 is adjusted prior to operation of the compensator and after adjustment is locked in position. Accordingly, the output of divider 39 is sin E/cos E or tan E, and this is multiplied in multiplier 40 by the output of demodulator and filter 19, which is sin (TB). Thus the output of multiplier 40 is [sin (E) sin (TB)]/cos (E) and this output is provided as an input to multiplier 38 where the AC component of the signal is reinserted. The output of multiplier 40 is connected to multiplier 38 through potentiometer 66, which inputs the roller path inclination angle A, and through sine function generator 67 which improves the approximation of the correction signal prior to interfacing with the existing synchro units in the gun mount. By way of example, divider 39 and multipliers 37, 38, and 40 might be an Analog Multiplier/Divider Model 107C, manufactured by Hybrid Systems Corp., Burlington, Mass, which can perform either multiplication or division according to the method of connecting the input and output connections.

OUTPUT INTERFACE SECTION The output interface section develops the proper signal levels for the compensator outputs. The signal levels which were reduced to less than 10 volts for processing by the various circuits and the analog computer components must be amplified to the gun synchro levels accepted by a regulator amplifier of the gun mount. One output amplifier and related circuitry 71 is provided for train signals and another output amplifier and related circuitry 72 is providedfor elevation signals. As both amplifiers are similar, the following discussion relates to train output amplifier and related circuitry 71.

Transformer 73 steps up the output voltage from multiplier 38 while amplifier 70 preserves linearity during power amplification. Crossover distortion is eliminated by the circuitry consisting of resistors 74 and 75,

capacitors 76 and 77, and diodes 78 and 79. A bias current through resistor 74 splits through diode 78 and transistor 81 to maintain a small current through the collector of transistor 81. A similar combination of current flows out through resistor 75. The output load on amplifier is slightly less than 5K ohms. Diodes 78 and 79 provide a voltage offset such that no crossover is necessary before current is conducted by transistor 81 and 82. Capacitors 76 and 77 maintain high frequency integrity across diodes 78 and 79 at a high rate of change in voltage. Resistors 83 and 84 are provided to prevent thermal runaway of transistors 81 and 82.

OPERATION Before the roller path compensator is placed in operation, an inclined gun mount is checked to determine roller path inclination angle (A) and the location of the high point (B). The inclination angle is set by adjusting potentiometers 66 and 68 which, by way of example, might be a dual potentiometer having a common shaft. The high point location angle B is set in the compensator by means of synchro differential transmitter 22. Once the values for A and B have been set into the compensator, these adjustments will not be changed unless battery alignment checks indicate that the roller path inclination has changed.

With the gun mount and compensator in operation, reference isolation amplifiers 11 and 12 scale down the VAC RMS input from ships reference to a usable 8 VAC RMS. Outputs from amplifiers 11 and 12 are fed into reference squaring amplifiers l3 and 14 which transform their sine wave inputs into a square wave at the fundamental frequency. The outputs from squaring amplifiers l3 and 14 are demodulated and filtered and then fed to the analog computation section. Divider 39 divides sin (E) by cos (E) which is then fed to multiplier 40. Multiplier 40 also receives an input from the train gun orders which has connected through differential transmitter 22 and sine/cosine generator 16, and multiplier 40 provides the output [sin E sin (TB)]/cos E. Potentiometer 66 is used to set in angle A and the output of multiplier 40 is connected through potentiometer 66 and sine function generator 67 to multiplier 38. Sine function generator 67 improves the output signal prior to interfacing with the existing synchro unit in the gun mount and multiplier 38 is provided to reinsert the AC component of the signal. The output signal from multiplier 38 is amplified to the synchro level accepted by the regulator amplifier of the gun mount.

Likewise, the elevation corrections are amplified, demodulated and filtered and AC is reinserted with the proper phase in multiplier 37. The output of multiplier 37 is in the form cos (TB) and this output is connected to potentiometer 68 where the value for A is inserted. The output is then amplified to the synchro level accepted by the regulator amplifier of the gun mount.

We claim:

1. A roller path inclination compensator for providing correction signals to a train control transformer and an elevation control transfonner of a gun mount for compensating aiming error due to a roller path being inclined with respect to a horizontal reference plane comprising,

a first input channel receiving an elevation angle sigl En,

a second input channel receiving a train angle signal first means connected to said first input channel for forming a signal proportional to the tangent function of said elevation angle signal E,

a synchro differential transmitter providing a signal B which is proportional to the angular distance of the highest point of the inclined roller path with respect to a given starting point,

second means connected to said second input channel through said synchro differential transmitter for forming a first signal output proportional to the sine function of signal B subtracted from signal T and forming a second signal output proportional to the cosine function of signal B subtracted from signal T.

third means and fourth means each for forming a signal A which is proportional to the angle of inclination of said roller path with respect to a horizontal reference plane, said fourth means having an input connected to the second signal output of said second means and an output connected to said elevation control transformer for providing an elevation correction signal A Cos (T-B), and

multiplying means for combining the signal output of said first means and the first signal output of said second means and forming an output signal which is applied to said train control transformer through said third means 66 to provide a train correction signal A tan (E) sin (T-B).

2. A roller path inclination compensator as set forth in claim 1 wherein said first means for forming a signal proportional to the tangent function of said elevation angle signal E includes a sine/cosine generator for producing a first output signal proportional to the sine of said elevation angle signal E and a second output signal proportional to the cosine of said elevation angle signal E, and means for dividing said first output signal by said second output signal.

3. A roller path inclination compensator as set forth in claim 1 wherein said third means and fourth means are potentiometers. 

1. A roller path inclination compensator for providing correction signals to a train control transformer and an elevation control transformer of a gun mount for compensating aiming error due to a roller path being inclined with respect to a horizontal reference plane comprising, a first input channel receiving an elevation angle signal ''''E'''', a second input channel receiving a train angle signal ''''T'''', first means connected to said first input channel for forming a signal proportional to the tangent function of said elevation angle signal ''''E'''', a synchro differential transmitter providing a signal ''''B'''' which is proportional to the angular distance of the highest point of the inclined roller path with respect to a given starting point, second means connected to said second input channel through said synchro differential transmitter for forming a first signal output proportional to the sine function of signal ''''B'''' subtracted from signal ''''T'''' and forming a second signal output proportional to the cosine function of signal ''''B'''' subtracted from signal ''''T''''. third means and fourth means each for forming a signal ''''A'''' which is proportional to the angle of inclination of said roller path with respect to a horizontal reference plane, said fourth means having an input connected to the second signal output of said second means and an output connected to said elevation control transformer for providing an elevation correction signal A Cos (T-B), and multiplying means for combining the signal output of said first means and the first signal output of said second means and forming an output signal which is applied to said train control transformer through said third means 66 to provide a train correction signal A tan (E) sin (T-B).
 2. A roller path inclination compensator as set forth in claim 1 wherein said first means for forming a signal proportional to the tangent function of said elevation angle signal E includes a sine/cosine generator for producing a first output signal proportional to the sine of said elevation angle signal E and a second output signal proportional to the cosine of said elevation angle signal E, and means for dividing said first output signal by said second output signal.
 3. A roller path inclination compensator as set forth in claim 1 wherein said third means and fourth means are potentiometers. 